The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 100 47 369.5, filed on Sep. 25, 2000, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates to a roll to be used in the drying section of a machine for producing a material web, e.g., for guiding and holding a paper web being impacted by a drying gas. The roll has a jacket, which, when in operation, the material web is guided over to partially wrap the roll. The roll also includes gas penetration openings and a device for supplying gas through the roll jacket.
2. Discussion of Background Information
Such rolls are used, e.g., as suction guiding rolls in drying sections in which the material web is dried by jet impingement drying, i.e., blowing the material web with drying air. When the suction guidance roll is provided with suction, the material web is held against the roll and can be guided by the roll in the desired manner.
For this purpose, the interior of the suction guidance roll is embodied in a hollow manner and is normally connected to a suction device by way of the roll bearings. This requires relatively large bearing pins and corresponding bearing support for the suction guidance roll.
Therefore, it is also known to provide the interior of the suction guidance roll with suction by a suction box located outside the roll. However, in this regard, the entire inner chamber of the suction guidance roll is provided with suction. Therefore, the suctioned volume depends on the diameter of the roll and is generally relatively large. This has especially negative effects in the start-up phase because a relatively long time elapses before a desired underpressure is achieved in the roll.
The present invention provides a roll of the type mentioned at the outset that does not exhibit the above-noted disadvantages. In particular, the start-up phase should be shortened. Moreover, the flow rate of the gas should be optimized and a simple construction of the roll should be attained.
Accordingly, the present invention includes a second, gas-tight jacket in the interior of the roll jacket that forms a ring chamber together with the outer roll jacket. The ring chamber is sealed off from the interior of the inner jacket in a gas-tight manner.
By providing a second, gas-tight jacket in the interior of the roll jacket and, due to the ring chamber formed thereby, which is sealed off from the interior of the inner jacket, the suctioned volume of the roll can be considerably reduced as compared to known rolls. For example, the suctioned space can now include only approximately 10 to approximately 15% of the total volume. A desired underpressure can thus be built up in a shorter time than in the case of known rolls. Moreover, the flow rate of the suctioned air over the size of the intermediate chamber can be brought to a desired amount. In particular, this results in short reaction times upon the introduction of a material web, for example, after the interruption of production due to a web tear or the like.
A further advantage lies in the fact that the roll can thus have a relatively simple construction because the main portion of the roll has only a carrying and support function.
In particular, the roll according to the invention is used as a suction guiding roll for guiding and holding a material web in a drying section in which the material web is dried by jet impingement drying. However, the roll according to the invention can also be used for flow-through drying of a material web, in which a drying gas, e.g., air, is fed through the material web.
It is possible to feed the drying gas through the material web into the intermediate chamber of the roll according to the invention, in particular from outside. Furthermore, the roll is preferably embodied as a suction roll in that a suction device is attached to it. However, instead of this, it is also possible to provide a blowing zone in the region of the wrapping of the outer roll jacket by the material web, e.g., to arrange a blow box there. In this manner, it is also possible to feed a drying gas from the outside through the material web into the intermediate chamber. It is furthermore possible to combine such a blowing zone with a suction device connected to the intermediate-chamber.
If a suction device is used, it is preferably attached to the intermediate chamber on the face end. This simplifies the construction of the roll and prevents a large diameter of the bearings. In this manner, it can be particularly preferred for a suction box to be provided that is aligned with the intermediate chamber. Connective lines between the suction device and the intermediate chamber may therefore be omitted.
In principle, however, the roll according to the invention can also be constructed for the purpose of feeding the drying gas from the intermediate chamber, through the material web, and outwards. In this case, the material web is pressed against the roll by a drying wire.
Preferably, the roll in this case can also be embodied or formed as a blowing roll in that a blowing device is attached to the intermediate chamber. In this case as well, the blowing device is preferably attached to the intermediate chamber on the face side in order to achieve a simple construction of the roll.
It is also particularly preferred for a blow box to be provided that is aligned with the intermediate chamber. This in turn makes it possible for connective lines between the blow box and the intermediate chamber to be omitted.
Instead of a blowing device connected to the intermediate chamber, a suction zone can be provided in the wrapping region of the roll jacket. For example, a suction box can be arranged there. In this manner, it is also possible for drying gas to be supplied from the intermediate chamber, through the material web, and outwards. Such a suction zone can also be combined with a blowing device attached to the intermediate chamber.
In order to prevent waste flows, the blow box and suction box are each sealed off from the outside, e.g., by sealing brushes or doctors. Moreover, covers fixed in the intermediate chamber for the throughput openings of the outer roll jacket can preferably be provided for the region of the roll not wrapped by the material web. This also prevents waste flow and improves the effectiveness of the device.
In order to support the two roll jackets, it is preferable for a central carrier to be provided that extends along the longitudinal axis of the roll, upon which the two roll jackets are supported such that they may be rotated around their longitudinal axes. A particularly advantageous construction results when spoke-like support elements are arranged in the interior of the inner jacket, by way of which the inner jacket is supported on the carrier. Moreover, it is also preferable for the outer jacket to be carried by the internal jacket.
Finally, the size of the intermediate chamber can preferably be selected to correspond to a desired flow rate of the gas. In particular, a greater flow rate and faster reaction time can be achieved by decreasing the size of the inner chamber.
The present invention is directed to a roll for a drying section of a machine for producing a material web. The roll includes a jacket having a plurality of throughput openings, a device for supplying gas through the jacket, and a second jacket located within the jacket being arranged to form a ring chamber with the jacket. The second jacket is gas tight to seal the ring chamber in a gas-tight manner from an interior of the second jacket.
In accordance with a feature of the instant invention, during operation, the material web may at least partially wrap the jacket.
According to another feature of the present invention, the roll can be structured and arranged for guiding and holding the paper web while being impinged by a drying gas,
The material web is guided over at least a portion of the jacket and a gas may be supplied by the gas supply device from outside through the material web into the ring chamber.
According to another feature, a gas can be supplied from outside of the jacket into the ring chamber.
Further, a suction device can be coupled to the ring chamber. The suction device may be coupled to the ring chamber on a face end. The suction device can include a suction box aligned with the ring chamber.
The material web may be guided to at least partially wrap around the jacket and a blowing zone can be arranged in a region in which the material web wraps the jacket. The blowing zone may be formed by a blow box. Further, the blow box can be sealed against waste flows with lateral seals. The lateral seal may include at least one of sealing brushes and doctors.
The material web can be guided over at least a portion of the jacket and a gas may be supplied by the gas supply device outwardly from the ring chamber through the material web.
In accordance with still another feature of the invention, a gas can be supplied outwardly from the ring chamber.
According to a further feature of the present invention, a blowing device may be coupled to the ring chamber.
A blowing device can be coupled to an end face of the ring chamber. Further, the blowing device may include a blow box aligned with the ring chamber.
Moreover, the material web can be guided to at least partially wrap the jacket, a gas can be supplied outwardly from the ring chamber through the material web, and a suction zone may be arranged in a region in which the material web wraps the jacket. The suction zone can be formed by a suction box. Further, the suction box may be sealed against waste flows with lateral seals. The lateral seal can include at least one of sealing brushes and doctors.
In accordance with a further feature of the instant invention, fixed coverings for the throughput openings may be located in the inner chamber. The material web can be guided to at least partially wrap the jacket, and the fixed coverings may be arranged in a region of the jacket which is not wrapped by the material web.
According to a still further feature of the invention, a central carrier can be arranged to extend along a longitudinal axis of the roll. The roll jacket and the second jacket may be rotatably supported on the central carrier. Spoke-like support elements may be arranged in an interior of the second jacket, and the spoke-like support elements can be structured and arranged to support the second jacket on the central carrier.
In accordance with another feature of the present invention, the jacket can be carried by the second jacket.
According to still another feature, a size of the ring chamber can correspond to a desired gas flow speed.
The ring chamber size can be between approximately 10 to approximately 15% of a volume of an entire interior of the jacket.
The present invention is directed to a dryer section in a machine for producing a material web. The dryer section includes a roll having an outer jacket with a plurality of throughput openings structured and arranged for gas flow and an inner jacket located within the jacket being arranged to form a ring chamber with the outer jacket, in which the inner jacket is gas tight to seal the ring chamber in a gas-tight manner from an interior of the inner jacket. A wire is arranged to at least partially wrap the outer jacket, such that the wire is structured and arranged to guide the material to at least partially wrap the outer jacket.
According to a feature of the invention, a blowing device can be arranged outside of the outer jacket in a region in which the material web wraps the outer jacket. Gas can be supplied through the material web and into the ring chamber. A suction device may be coupled to the ring chamber. The blowing device can include at least one blowing hood arranged to impinge the material web with hot air. Further, the suction device can be coupled to a face end of the ring chamber.
In accordance with another feature of the instant invention, a blowing device can be arranged to blow gas outwardly from the ring chamber and through the material web. A suction device may be arranged in a region in which the material web wraps the outer jacket. The blowing device is coupled to the ring chamber. Further, the blowing device may be coupled to a face end of the ring chamber.
The present invention is directed to a process for drying a material web in an apparatus that includes a roll having an outer jacket with a plurality of throughput openings, a device for supplying gas through the outer jacket, and an inner jacket, located within the outer jacket, arranged to form a ring chamber with the outer jacket, in which the inner jacket is gas tight to seal the ring chamber in a gas-tight manner from an interior of the inner jacket. The process includes guiding the material web to at least partially wrap the roll, blowing air through the outer jacket and one of into and out of the ring chamber in a region in which the material web wraps the roll, and blowing air through the material web in the wrap region of the roll.
According to a feature of the invention, the apparatus can further include a blowing device arranged outside of said outer jacket in the wrap region of roll, and the process may further include blowing gas into the ring chamber. The apparatus can further include a suction device coupled to the ring chamber, and the process may further include suctioning the ring chamber. The blowing device may include at least one blowing hood, and the process can further include impinging the material web with hot air, and suctioning the hot air passing through the material web and into the ring chamber. The ring chamber can be suctioned at a face end of the ring chamber.
In accordance with yet another feature of the present invention, the apparatus can further include a blowing device, and the process may further include blowing gas outwardly from the ring chamber. The apparatus can further include a suction device arranged in a region in which the material web wraps the outer jacket, and the process may further include suctioning the air exiting the ring chamber. The gas blown out from the ring chamber may be supplied at a face end of the ring chamber.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.